Update README: Add UltraData-Math-L2 subset config

README.md

@@ -26,6 +26,8 @@ configs:
   data_files: "data/UltraData-Math-L3/QA-Synthetic/*.parquet"
 - config_name: UltraData-Math-L3-Textbook-Exercise-Synthetic
   data_files: "data/UltraData-Math-L3/Textbook-Exercise-Synthetic/*.parquet"
+- config_name: UltraData-Math-L2
+  data_files: "data/UltraData-Math-L2/**/*.parquet"
 - config_name: UltraData-Math-L1
   data_files: "data/UltraData-Math-L1/**/*.parquet"
 default_config_name: UltraData-Math-L3-Conversation-Synthetic